Pressure balancing means for pump impellers



United States Patent 3,387,564 PRESSURE BALANCING MEANS FOR PUMP IMPELLER Warren Heathcote De Lancey, 4205 S. Murray Ridge Road, Elyria, Ohio 44035 Filed Au 4, 1966, Ser. No. 570,240 1 Claim. (Cl. 103-103) ABSTRACT OF THE DISCLOSURE In the drawings the single figure is a fragmentary sectional view taken through a fluid compressor pump having the invention embodied therein.

The illustrated compressor is similar in general construction to the compressor shown in US. Patent 3,081,932 issued Mar. 19, 1963. It comprises an annular cup-like housing having a bottom wall 12 and a cuplilre extension 14 forming an inlet chamber 16 for refrigerant gas coming from the evaporator of a refrigeration system through the inlet fitting 18. Arranged within housing 10 is a compressor motor comprising a laminated stator 20 having windings 22, and a laminated rotor 24 having windings 26. Rotor 24 is carried on a vertical rotor shaft 28 which is provided with upper and lower thrust washers 30 and 32 engaging respective ends of a tubular support 34. Plastic sleeve bearings 36 and 38 are mounted in tubular support 34 to carry the radial load from shaft 28. Tubular support 34 is formed integrally with four radial struts 40 carried by the cup-like motor support 42, two or more screws 44 being threaded into the motor support to hold the motor thereon.

Shaft 28 is provided with a reduced lower end portion 46 which carries the hub portion 48 of a centrifugal liquid impeller pump 50. The back wall 52 of the impeller is provided with eight backwardly curved vanes 54 which draw liquid into the eye of the wheel designated generally by numeral 56. The liquid is initially drawn from the liquid source or sump 53, from whence it flows through the spaces between ribs 40 to the impeller eye 56 as denoted by the arrows. The liquid is discharged through the outer peripheral opening of the wheel into an annular diffusion passageway 60 which merges into a vertical annular passageway 62. Passageways 60 and 62 are formed by the outer face of cup-like sub-housing 64 and the inner face of housing 10.

As the liquid discharges from wheel it entrain's gas from chamber 16. The liquid-gas mixture diffuses and decelerates as it moves through annular passageways and 62 so that velocity pressure is converted to static pressure. When the mixture reaches chamber 66 the high pressure gas separates from the liquid and is discharged through the outlet fitting 66 leading to the condenser of the refrigeration system. The liquid flows downwardly over and through the motor to the liquid sump 58, from whence it is recirculated to the impeller.

The invention The construction thus far described is generally conventional. This invention concerns a pressure-balancing means for minimizing such axial fluid pressure forces on the rear wall 52 of the impeller as would produce premature wear on thrust washers 30 and 32. The illustrated pressure-balancing means comprises an upper tubular sealing element 70 floatably positioned in the opening 72 of the wall structure 42. The lower edge of element 70 engages the upper side face 74 of the impeller to seal the joint therebetween. The joint between wall opening 72 and sealing element 70 is sealed by an annular pliable sealing element 76 shown as an elastomeric sealing ring sold under the tradename Quad-Ring. It is believed that other functionally equivalent sealing elements could be employed.

To maintain the seal between annular element 70 and impeller side face 74 there is provided a biasing means in the form of a spring Washer 78. This washer comprises an outer annular portion 80 seated on wall structure 42, and a series of spring fingers 82 radiating inwardly from portion 80 to engage the flange 84 formed on sleeve 70. The spring fingers exert a downward biasing action on element 70 to maintain a desired sealing pressure against impeller side face '74.

The pressure-balancing means comprises a second tubular sealing element 70a identical with the first element. Element 70a is floatably positioned in opening 72a formed in hollow wall structure 86, said wall structure being suitably spot-welded to the bottom wall of sub-housing 14 to retain it in a fixed position. As shown in the drawing, element 70a is biased upwardly by a second spring washer 78; the joint between element 70a and opening 72a is sealed by a second sealing element '76.

The impeller 50 is modified to have one or more fluid openings 88 formed in its back wall, whereby inlet liquid is enabled to flow from the inlet eye 56 into the hollow wall structure 86. It will be seen that annular sealing elements 70 and 70a have substantially the same circumscribed areas so that the inlet fluid pressure is balanced across the upper and lower side faces of the impeller. During service some of the liquid admitted to inlet eye 56 will flow through the opening 80 and fill up the chamber formed by wall structure 86. This chamber pressure will oppose the downward pressure exerted against back wall 52 of the impeller, and will relieve the impeller shaft 28 of any substantial axial loading due to fluid pressure forces. As a result, the bearing 30 will have a relatively light loading thereon, and will remain in service for a considerably longer time than a corresponding bearing used in a non-balanced impeller environment.

The invention has been illustrated in a particular type of pump wherein liquid is circulated within a compressor to entrain gas to be compressed. It is contemplated however that the invention would be employed in other pumping devices for liquid or gas. Some variation in structure and arrangement may be employed. For example, the inlet fluid could be admitted to the hollow structure 86 through passageways formed in shaft 46 and hub 48 instead of through openings 88. Other minor variations in structure and configuration could be resorted to without departing from the spirit of the invention as contemplated by the appended claim.

I claim:

1. A fluid pump comprising a stationary wall structure (42) having a circular opening (72) therein; a first cylindrical tubular sealing element (70) floatably positioned within said opening for axial movement; a second stationary wall structure (86) having a second circular opening (72a) axially aligned with the aforementioned opening (72); said openings having the same diameter; a second cylindrical tubular sealing element (70a) floatably positioned within the second opening for axial movement; a vaned impeller (50) positioned coaxially of the circular openings in the space between the two wall structures (42) and (86); said impeller having first and second side faces (74) and (52) engaged with the opposed edges of the respective sealing elements (70) and (763a) to seal the respective joints therebetween; said impeller side face (74) having a fluid entrance opening which is substantially the same diameter as the inner diameter of the first mentioned sealing element (70) whereby to promote flow continuity as the fluid passes from the sealing element into the impeller; a fluid opening (88) in the impeller allowing the pressure within the impeller to be communicated to the space within the second tubular sealing element; each tubular sealing element having an outwardly radiating flange (84); a first annular leaf spring (82) having its outer peripheral area positioned against wall structure (42) and its inner peripheral area positioned against the flange on sealing element (78) to bias said element toward engagement with the impeller; a second annular leaf spring (82) having its outer pe- Iipheral area positioned against wall structure (86) and its inner peripheral area positioned against the flange on sealing element (70a) to bias said element toward engagement with the impeller; 21 first pliable sealing ring (76) mounted within Wall structure (42) in contact with the outer face of element (70); and a second pliable sealing ring (76) mounted within wall structure (86) in contact with the outer face of element (70a).

References Cited UNITED STATES PATENTS 1,936,771 11/1933 Schellens. 2,006,727 7/ 1935 Ardrey. 2,475,316 7/ 1949 Garraway. 2,817,544 12/ 1957 Von Der Nuell. 3,066,612 12/ 1962 Haentjens. 3,081,932 3/1963 De Lancey.

HENRY F. RADUAZO, Primary Examiner. 

